Oracle Database 11g FSFO adds support for Maximum Performance mode (async redo transfer), providing the flexibility to trade durability for performance. Commit latency is not affected by redo transfer, but committed transactions whose redo has not been received by the standby will be lost during failover. FSFO configurations in Maximum Performance mode may limit potential data loss by specifying the maximum allowable age of transactions that are lost during a failover. For example, if the limit specified is 30 seconds (the default), FSFO guarantees that all transactions that committed prior to 30 seconds ago are preserved during failover. The minimum allowable limit is 10 seconds.

We want the partial functionality of FSFO, I mean to say that we want to automate the failover using observer FSFO Configuration but same time Instead of relay on Auto reinstate feature, we want to rebuild the new standby manually once old primary is comes up.